青藏500kV输电工程沿线冻土工程特性及其对策探讨

A Discussion on Permafrost Engineering Characteristics along Qinghai-Tibet 500 kV Power Transmission Line and Countermeasures

根据青海-西藏500 kV直流联网工程输电线路沿线多年冻土区已有研究成果及现场实际勘察结果,结合输电线路工程特点对沿线冻土工程地质条件、存在的冻土工程问题,以及对策进行了较为系统研究。研究表明:输电线路沿线跨越540 km的连续片状多年冻土区和80 km的岛状多年冻土区,其中高含冰量冻土区占一半左右,低含冰量冻土区占25%;工程稳定性差的冻土地温带分布广;沿线的工程地质问题普遍存在,冻胀融沉是输电线路塔基失稳的主要原因,其中冻拔问题将是输电线路工程面临的新问题;不良冻土现象广泛分布于沿线,对线路构成较大危害;在气候变暖条件下,冻土退化较为显著,对输电线路的长期稳定性产生负面影响。同时,结合地下冰发育规律和工程特点,提出了输电线路选线选位的原则,以及塔基设计建议方案,并针对可能存在的工程问题给出施工建议。其研究成果将为输电线路的施工建设提供科学依据。

According to permafrost research and actual research findings along the Qinghai-Tibet 500 kV DC power transmission line, and combining the engineering characteristics of the transmission line, the permafrost engineering geological conditions, permafrost engineering problems and countermeasures have been studied in detail. Research shows that the power transmission line spans 550 km permafrost zone and 80 km island permafrost zone, ice-rich permafrost accounts for more than 50% of the total permafrost area and the ice-poor accounts for 25%; there is a wide distribution of frozen soil temperature zone of poor engineering stability. Permafrost problems exist universally along the line, the main reasons for instability of the transmission line are frost heave and thaw settle- ment, the frozen lift will be a new problem faced by the transmission line; along the line there are many adverse permafrost phenome- na, which will endanger the line; and under warming conditions, permafrost degradation is more obvious, which produces a negative impact on the long-term stability along the line. Meanwhile, combining the rules of ground ice and engineering characteristics, the principles of choosing the transmission line and the proposals of ground design have been discussed, and based on the possible engi- neering problems, construction suggestions are put forward. Research results have provided a scientific basis for the construction of the transmission line.